Explanation:
Near the centre of this sharp cosmic portrait, at the heart of
the
Orion Nebula, are four hot, massive stars
known as
the Trapezium.
Tightly gathered within a region
about 1.5 light-years in radius,
they dominate the core of the dense Orion Nebula Star Cluster.
Ultraviolet ionizing radiation from the Trapezium stars,
mostly from the brightest star
Theta-1
Orionis C
powers the complex star forming region's entire visible glow.
About three million years old, the Orion Nebula Cluster was
even more compact in its younger years and a
dynamical study
indicates that
runaway stellar collisions
at an earlier age may have formed a black hole
with more than 100 times the mass of the Sun.
The presence of a black hole within the cluster
could explain the observed high velocities of the Trapezium stars.
The Orion Nebula's distance of some 1,500 light-years
would make it the closest known black hole to planet Earth.